The electric vehicles and hybrid vehicles that mount an electric motor as a driving source require mounting on a vehicle a battery pack that accommodates batteries capable of storing large capacity electric powers, because electric powers are to be supplied to vehicle mounted electric parts in addition to the electric motor.
This type of battery pack includes one that adopts a form of being accommodated inside a concave recess formed on a floor panel (see, for example, Japanese Patent Application Publication No. 2010-89567).
In such a vehicle mounting structure for a battery pack, a form of being installed in a luggage room on a rear portion side of the vehicle (there are cases where it is on a front portion side depending on a structure of the vehicle) is frequently used, in order to secure as much space as possible in the vehicle interior for passengers.
Also, in recent years, the vehicle is devised to make deformation of its exterior members functioning as cushions, by securing a large shock absorbing space for a time of a crash between the exterior members and the internal parts. In particular, it is advantageous for a space inside the luggage room to be secured large as a measure against a crash from a rear side.
Then, it is common to install a pair of left and right coil springs on front and rear of the vehicle. For this reason, there is a need to install the battery pack in such a way that the pair of left and right coil springs is avoided, so that there is a limitation on the installation position. For example, in the case of installing the battery pack between the coil springs, there is a need to make a width of the exterior casing smaller than the separation interval of the coil springs.
For this reason, in the case of the large capacity battery pack, if it is installed on a rear side of the coil springs it would come in close proximity to the exterior members such as a hatchback door of the vehicle, whereas if it is installed between the coil springs it would become long in the front and rear direction and as a result it would come in close proximity to the exterior members of the vehicle. In short, in the case of the large capacity battery pack, a large shock absorbing space for a time of a crash between the battery pack and the exterior members of the vehicle cannot be secured.
By the way, for this vehicle mounting structure for a battery pack, there is a case of adopting a form in which the battery pack is accommodated by forming an opening on the floor panel, so that a space of the luggage room will not be occupied as much as possible. In this case, there are occasions in which places with a narrow width and a low rigidity will be created outside that opening of the floor panel and the inconvenience of having vibrations of the floor panel increased due to vibrations from the vehicle body side such as the coil springs arises.
Note that, in one that is described in Japanese Patent Application Publication No. 2010-89567, it is substantially a form of recessing the floor panel so that it is difficult to recess it largely and as a result it would occupy a large space inside the luggage room.